Studies on the effect of exogenous amino acid application on nematodes

Plant parasitic nematodes are considered as key pathogens in agricultural crop production. They cause substantial yield losses in numerous crops and across all climatic regions worldwide. Antagonistic effects on various life stages of economically relevant plant pathogenic nematode species were reported for different amino acids (aa). In order to screen for effects induced by exogenous application and to reveal their underlying mechanistic methionine (Met), lysine (Lys), threonine (Thr), isoleucine (Ile), 2-ketobutyric acid (Ket), homoserine (Hom) and tryptophan (Trp) were tested on the free-living nematode Caenorhabditis elegans and the plant parasite Heterodera schachtii. Try applications reduced the activity and development of C. elegans, whereas only Ket affected the activity of H. schachtii. Interestingly, soaking J2 stage nematodes in aa solutions for twenty-four hours, induced a sex ratio change for both Lys isomers. The strongest effects were observed when aa were supplemented to the nutrient-medium in a monoxenic culture of the host plant, Arabidopsis thaliana. This approach reduced the number of female nematodes per plant for Iso, Met, Thr, and Ket. Additionally, slight negative effects could be detected on the adult female sizes. Interestingly, these effective aa all belong to the aspartate pathway. Herein, in particular the plant inherent enzyme methionine-γ-lyase (MGL) was identified as possible key functional element

Transcriptome and Parasitome Analysis of Beet Cyst Nematode Heterodera schachtii

Beet cyst nematodes depend on a set of secretory proteins (effectors) for the induction and maintenance of their syncytial feeding sites in plant roots. In order to understand the relationship between the beet cyst nematode H. schachtii and its host, identification of H. schachtii effectors is crucial and to this end, we sequenced a whole animal pre-infective J2-stage transcriptome in addition to pre- and post-infective J2 gland cell transcriptome using Next Generation Sequencing (NGS) and identified a subset of sequences representing putative effectors. Comparison between the transcriptome of H. schachtii and previously reported related cyst nematodes and root-knot nematodes revealed a subset of esophageal gland related sequences and putative effectors in common across the tested species. Structural and functional annotation of H. schachtii transcriptome led to the identification of nearly 200 putative effectors. Six putative effector expressions were quantified using qPCR and three of them were functionally analyzed using RNAi. Phenotyping of the RNAi nematodes indicated that all tested genes decrease the level of nematodes pathogenicity and/or the average female size, thereby regulating cyst nematode parasitism. These discoveries contribute to further understanding of the cyst nematode parasitism

Transcriptome and Parasitome Analysis of Beet Cyst Nematode Heterodera schachtii

Beet cyst nematodes depend on a set of secretory proteins (effectors) for the induction and maintenance of their syncytial feeding sites in plant roots. In order to understand the relationship between the beet cyst nematode H. schachtii and its host, identification of H. schachtii effectors is crucial and to this end, we sequenced a whole animal pre-infective J2-stage transcriptome in addition to pre- and post-infective J2 gland cell transcriptome using Next Generation Sequencing (NGS) and identified a subset of sequences representing putative effectors. Comparison between the transcriptome of H. schachtii and previously reported related cyst nematodes and root-knot nematodes revealed a subset of esophageal gland related sequences and putative effectors in common across the tested species. Structural and functional annotation of H. schachtii transcriptome led to the identification of nearly 200 putative effectors. Six putative effector expressions were quantified using qPCR and three of them were functionally analyzed using RNAi. Phenotyping of the RNAi nematodes indicated that all tested genes decrease the level of nematodes pathogenicity and/or the average female size, thereby regulating cyst nematode parasitism. These discoveries contribute to further understanding of the cyst nematode parasitism.This article is published as Elashry, Abdelnaser M., Samer S. Habash, Paramasivan Vijayapalani, Nahal Brocke-Ahmadinejad, Roman Blümel, Arun Seetharam, Heiko Schoof, and Florian MW Grundler. "Transcriptome and Parasitome Analysis of Beet Cyst Nematode Heterodera schachtii." Scientific Reports 10 (2020): 3315. DOI: 10.1038/s41598-020-60186-0. Posted with permission.</p